#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/wait.h>

void writer(int wfd)
{
  const char* str = "hello father,I an child,I am writing!";
  char buffer[128];
  int cnt = 0;
  pid_t pid = getpid();
  while(1)
  {
    snprintf(buffer,sizeof(buffer),"message:%s,pid:%d,count:%d\n",str,pid,cnt);
    write(wfd,buffer,strlen(buffer));
    cnt++;
    sleep(2);
  }
}

void reader(int rfd)
{
  char buffer[1024];
  while(1)
  {
    ssize_t n = read(rfd,buffer,sizeof(buffer)-1);
    printf("father get a message:%s",buffer);
  }
}

int main()
{
  //父进程创建管道
  int pipefd[2];
  int n = pipe(pipefd);
  if(n < 0) return 1;

  printf("pipefd[0]:%d,pipe[1]:%d\n",pipefd[0],pipefd[1]);//3,4
  //                                        r         w
  //父进程fork出子进程
  pid_t id = fork();
  if(id == 0)
  {
    //child:w
    close(pipefd[0]);

    writer(pipefd[1]);

    exit(0);
  }
  //father:r
  close(pipefd[1]);
  reader(pipefd[0]);
  wait(NULL);
  return 0;
}

